By ROBERT MCCLURE, SEATTLE POST-INTELLIGENCER REPORTER

Published 10:00 pm, Monday, August 15, 2005

Pollution of Puget Sound appears to be coming increasingly from ordinary, everyday citizens driving around in their cars rather than industrial polluters, a state study released Monday says.

The study summed up the results of tests on mud and sand at the bottom of Puget Sound over a 12-year period. Toxic metals thought to be associated with industrial polluters waned, while a class of chemicals called polycyclic aromatic hydrocarbons, or PAHs, increased.

The second class of chemicals comes mostly from burning coal and petroleum, particularly car exhaust.

"This serves to put up a red flag for highly important issues that are happening," said Maggie Dutch, a state Department of Ecology scientist who studies marine sediments. "It's a really important thing to know that the levels of these compounds are increasing, and it's probably associated with people driving."

PAHs can get from a car's tailpipe into the Sound in basically two ways: Either they drift around until they fall directly into the water, or they land on the ground and are washed by rain into the Sound or its tributaries.

Ecology's findings mirror those of researchers nationwide with the U.S. Geological Survey.

As the Clean Air Act and Clean Water Act slashed pollution spewing from smokestacks and waste-discharge pipes over the past three decades, levels of toxic metals have fallen and PAHs have increased.

It all adds up to yet another reason to drive as little as possible, Ecology says.

"It's happening with some regularity that we're getting some sources of pollution under control and others are getting worse at the same time," Ecology Director Jay Manning said. "The kind of pollution that's getting worse, it's probably because of a lot of repetitive activities by people like you and I."

The testing began in 1989. The most recent results were from 2000. More testing has continued, although results are not yet available. Sediments were scooped up at 10 sites -- stretching from Bellingham to Shilshole Bay to the Olympia area.

The report is one of a series of results of the state's multiyear pollution-monitoring programs for the Sound.

Eric Crecilius of the Batelle Marine Science Lab in Sequim, who was not involved in the Ecology study but has studied the evolution of pollution in Puget Sound sediments, said Ecology's hypothesis about the source of the PAH increase makes sense.

Originally PAHs spiked in the 1930s and 1940s as a result of people burning coal, he said. But as oil and later electricity replaced coal, PAH levels subsided, Crecilius said.

Overall, the Sound's sediments have grown cleaner over the past half-century or so, he said, partly because of the crackdown on pollution and partly because of the use of cleaner energy sources.

A reverse during the 1990s probably happened, he said, because "there's just more of us. ... I don't have anything to argue against that."

PAHs are just one component of a polluted mess that washes off the urban landscape in the Pacific Northwest's legendary rains.

Here, pavement contractors are using an asphalt-based parking lot sealant, he said, rather than the coal tar-based variety singled out by the Austin researchers as having the highest PAH levels.

"To my knowledge, there is no supplier of (coal-tar sealant) in the Seattle area," Sebaaly said.

His group has resisted what it calls the singling out of parking-lot sealants as PAH sources, because PAHs come from so many products, including car exhaust, roads -- even tires.

However, the report published earlier this summer in the journal Environmental Science & Technology said PAH levels on asphalt-sealed parking lots are about 10 times higher than those coming off unsealed asphalt or concrete parking lots.

The sealants provide a less expensive way to refinish a parking lot. They can be sprayed or painted on, as opposed to the much more involved process of laying down a whole new coat of asphalt.

David Johns, a co-author of the paper, said asphalt sealants are a source of PAHs, but the pollution runs off those surfaces at about one-tenth the rate it comes off the lots covered by coal-tar sealants.